A needle of length l m and mass m kg is placed horizontal on wter surface habing surface tension T Find T in terms of m, l (g acceleration due to gravity)

Options

A. `T=(mg)/(2l)`
B. `T=(mg)/(l)`
C. `T=(3mg)/(2l)`
D. `T=(m)/(2l)`

Answer

A

Explanation

`2T cos theta=mg`
`T=(mg)/(2 cos theta)`
`theta ` is very
`T=(mg)/(2l)`